With over 170,000 users in the last 12 months and over 2,300 resources including nearly 200 simulation tools, nanoHUB.org has established itself as the world’s largest Nanotechnology User Facility. Critical attributes for the success of such science gateways are open access, ease of use, utterly dependable operation, and diverse, high-quality content. Through nanoHUB.org, these attributes are realized, resulting in significant global knowledge transfer among researchers and from research to education. The impact and success of a science gateway can be measured and evaluated utilizing a variety of usage statistics, usage patterns, and analysis of citation data.